Yankees rookie Shelley Duncan may be a hit on the field, but the family of a 10-year-old Boston Red Sox fan says the slugger has struck out following a “joke” autograph, the Boston Herald reported.

According to young Red Sox fan Griffin Whitman, Duncan wrote “Red Sox Suck! Shelley Duncan” in his notebook during an autograph session before last Friday’s game between the two fierce rivals at Boston’s Fenway Park.

“It was cool to get his autograph,” Griffin told the Herald. “It didn’t make me feel happy when he wrote that.”

Duncan later tolk the Herald he was surprised that the boy and his family took offense to the autograph.

“I thought I was back in middle school or high school, where you try to make a joke or say something funny, and you end up saying something that gets you in trouble,” Duncan said. “I try to be interactive with people, be funny, have a good time and have a laugh.”

“It’s not always Yankees fans that have us sign stuff. I try to rile ’em up and be fun. I don’t expect anybody to make a big deal about it. Nobody ever has before.”

Yankees management had no comment when contacted by FOXNews.com on Monday.

Griffin’s mother, Karen, blasted the young Yankees slugger for setting a bad example.

“This is someone who wears the Yankee uniform and is on the payroll and should be setting an example for 10-year-olds,” she told the Herald.

Shelley Duncan Joke Autograph
Shelley Duncan Joke Autograph